Interchangeable lens, camera body, and camera system

ABSTRACT

An interchangeable lens includes a focus lens for changing a focus state of an object image, a driving unit for driving the focus lens, a lens controller for controlling the driving unit so as to move the focus lens forward and backward along the optical axis at a predetermined drive frequency, and a storage unit for storing therein drive frequency information representing a drive frequency at which the driving unit can control. A camera body obtains the drive frequency information from the interchangeable lens and performs control while referring to the drive frequency information.

TECHNICAL FIELD

The present invention relates to an interchangeable lens, a camera body,and a camera system. In particular, the present invention relates to aninterchangeable lens, a camera body, and a camera system that cansupport capturing of a moving image.

BACKGROUND ART

Patent Document 1 discloses an interchangeable lens type camera. A lensunit mountable to the camera has drive systems related to autofocusadjustment, auto exposure control and the like. Further, the lens unitmountable to the camera has status information of the lens unit. Withthis camera device, communication is done between the camera and thelens unit to exchange a variety of control information and the statusinformation, so that the lens unit is controlled from the camera side.

PRIOR ART DOCUMENT Patent Document

-   Patent Document 1: JP 04-280239 A

DISCLOSURE OF INVENTION Problems to be Solved by the Invention

As described above, Patent Document 1 discloses only the statusinformation of the drive system related to the autofocus adjustment, theauto exposure control and the like as the information owned by the lensunit. However, with such a structure, when capturing a moving image at apredetermined frame rate, it is uncertain whether or not the lens unitis capable of accepting the control corresponding to the frame rate.Accordingly, with such a structure, control cannot correctly be exertedover the lens unit from the camera side in capturing a moving image.

An object of the present invention is to provide an interchangeablelens, a camera body, and a camera system, in which the interchangeablelens can be controlled correctly by the camera body in capturing amoving image.

Means for Solving the Invention

In a first aspect of the present invention, an interchangeable lensmountable to a camera body is provided. The interchangeable lensincludes a focus lens configured to change a focus state of a subjectimage, a driving unit configured to drive the focus lens along anoptical axis, a lens controller configured to control the driving unitto move the focus lens forward and backward at a predetermined drivefrequency along the optical axis, and a storage unit configured to storedrive frequency information indicating a drive frequency at which thedriving unit can drive the focus lens.

In a second aspect of the present invention, a camera body to which aninterchangeable lens is mountable is provided. The interchangeable lensincludes a focus lens and storing drive frequency information indicativeof a drive frequency for driving the focus lens. The camera bodyincludes an imaging unit configured to capture a subject image at apredetermined imaging frequency, a receiving unit configured to receivean instruction as to the predetermined imaging frequency, an obtainingunit configured to obtain the drive frequency information from theinterchangeable lens, and a body controller configured to refer to thedrive frequency information obtained by the obtaining unit, determineswhether the focus lens can be driven at a drive frequency correspondingto the predetermined imaging frequency indicated by the instructionreceived by the receiving unit, and control an operation of the camerabody in accordance with a result of the determination.

In a third aspect of the present invention, a camera system including aninterchangeable lens and a camera body is provided. The interchangeablelens includes a focus lens configured to change a focus state of asubject image, a driving unit configured to drive the focus lens alongan optical axis, a lens controller configured to control the drivingunit to move the focus lens forward and backward at a predetermineddrive frequency along the optical axis, and a storage unit configured tostore drive frequency information on a drive frequency at which thedriving unit can drive the focus lens. The camera body includes animaging unit configured to capture a subject image at a predeterminedimaging frequency, a receiving unit configured to receive an instructionrelated to the predetermined imaging frequency, and a body controllerconfigured to control the camera body. The body controller requests thedrive frequency information from the lens controller. The lenscontroller sends the drive frequency information to the body controllerin response to the request from the body controller. The body controllercontrols an operation of the camera body by referring to the receiveddrive frequency information.

Effects of the Invention

According to the present invention, there can be provided aninterchangeable lens, a camera body, and a camera system, in which theinterchangeable lens can be controlled accurately by the camera body incapturing a moving image.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram of a camera system according to a firstembodiment.

FIGS. 2A and 2B are schematic diagrams for describing drive frequencyinformation.

FIG. 3 is a diagram showing a transmission and reception sequencebetween a body and a lens in an imaging preparation operation.

FIG. 4 is a flowchart of an operation of recording a moving image.

FIG. 5 is a diagram showing a display example of a warning message.

FIG. 6 is a diagram showing a display example of a warning message.

FIG. 7 is a table for describing drive frequency information representedby ratio to the control frequency.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, an embodiment of the present invention will be describedwith reference to the accompanying drawings.

First Embodiment

Hereinafter, a first embodiment in which the present invention isapplied to an interchangeable lens type camera system will be describedwith reference to the drawings.

1-1. Configuration 1-1-1. Overview

FIG. 1 is a block diagram showing a configuration of a camera systemaccording to a first embodiment of the present invention. A camerasystem 1 includes a camera body 100 and an interchangeable lens 200 thatis mountable to the camera body 100. The camera system 1 can generatemoving image data by periodically capturing image data with a CCD imagesensor 110. The camera system of the present embodiment can achievesuitable lens drive control in accordance with a frame rate that can besupported by the interchangeable lens 200 in capturing a moving image.

1-1-2. Configuration of Camera Body

The camera body 100 includes the CCD image sensor 110, a liquid crystaldisplay monitor 120, a camera controller 140, a body mount 150, a powersupply 160, and a card slot 170.

The camera controller 140 controls components such as the CCD imagesensor 110 in accordance with an instruction from an operational membersuch as a release button 130 to control the operation of the entirecamera system 1. The camera controller 140 sends a verticalsynchronizing signal to a timing generator 112. Concurrently, the cameracontroller 140 generates an exposure synchronizing signal. The cameracontroller 140 periodically sends the generated exposure synchronizingsignal to a lens controller 240 through the body mount 150 and a lensmount 250. The camera controller 140 uses DRAM 141 as working memory inperforming any control operation or image processing operation.

The CCD image sensor 110 generates image data by capturing a subjectimage being incident through the interchangeable lens 200. In otherwords, the CCD image sensor 110 performs exposures at a predeterminedtiming to capture a subject image and generate image data. The generatedimage data is digitized by an AD converter 111. The digitized image datais subject to predetermined image processing performed by cameracontroller 140. The predetermined image processing includes, forexample, a gamma correction process, a white balance adjustment process,a flaw correction process, a YC conversion process, an electronic zoomprocess, and a JPEG compression process.

The CCD image sensor 110 operates at a timing controlled by the timinggenerator 112. The operations of the CCD image sensor 110 include anoperation of capturing a still image, an operation of capturing athrough image, and the like.

Here, in capturing a moving image, the CCD image sensor 110 operates atthe timing corresponding to the frame rate selected by a frame rateselection dial 131. That is, the frame rate selection dial 131 receivesan instruction from a user as to a frequency of the CCD image sensor 110to capture a subject image (imaging frequency).

A through image is mainly a moving image and is displayed on the liquidcrystal display monitor 120 for the user to determine composition fortaking a still image.

The liquid crystal display monitor 120 displays an image represented byimage data for display subject to the image processing performed by thecamera controller 140. The liquid crystal display monitor 120 canselectively display both a moving image and a still image.

The card slot 170 can be loaded with a memory card 171. The card slot170 controls the memory card 171 under control of the camera controller140. The memory card 171 can store image data generated by the imageprocessing performed by the camera controller 140. For example, thememory card 171 can store JPEG image files. Further, the image data orimage file stored in the memory card 171 can be read, and the image dataor image file read from the memory card 171 are subject to the imageprocessing performed by the camera controller 140. For example, thecamera controller 140 decompresses the image data or image file obtainedfrom the memory card 171 to generate image data for display.

The power supply 160 supplies power to be consumed by the camera system1. The power supply 160 may be, for example, a dry battery, or arechargeable battery. Alternatively, the power supply 160 may externallysupply power through a power cord to the camera system 1.

The body mount 150 can mechanically and electrically be connected to thelens mount 250 of the interchangeable lens 200. The body mount 150 cansend and receive data to and from the interchangeable lens 200 throughthe lens mount 250. The body mount 150 sends an exposure synchronizingsignal which is received from the camera controller 140 to the lenscontroller 240 through the lens mount 250. The body mount 150 also sendsother control signals which are received from the camera controller 140to the lens controller 240 through the lens mount 250. For example, thebody mount 150 sends control information related to a drive frequency ofthe focus lens 230, which is received from the camera controller 140, tothe lens controller 240 through the lens mount 250. The body mount 150also sends a signal which is received from the lens controller 240through the lens mount 250, to the camera controller 140. For example,the body mount 150 receives drive frequency information (described indetail later) of the focus lens 230 in the interchangeable lens 200 fromthe lens controller 240 through the lens mount 250, and sends thereceived drive frequency information to the camera controller 140. Thatis, the camera controller 140 obtains the drive frequency informationfrom the interchangeable lens 200. The body mount 150 supplies the powerreceived from the power supply 160 to the entire interchangeable lens200 through the lens mount 250.

1-1-3. Configuration of Interchangeable Lens

The interchangeable lens 200 includes an optical system, the lenscontroller 240, and the lens mount 250. The optical system includes azoom lens 210, an OIS lens 220 (camera shake correction lens (opticalimage stabilizer)), and a focus lens 230.

The zoom lens 210 is a lens for changing the magnification of a subjectimage formed at the optical system. The zoom lens 210 includes a singleor a plurality of lenses. The drive mechanism 211 includes a zoom ringthat can be operated by the user, and the like. The drive mechanism 211transfers the operation of the user to the zoom lens 210 to move thezoom lens 210 in the optical axis direction of the optical system. Thedetector 212 detects an amount of drive of the drive mechanism 211. Thelens controller 240 can recognize the zoom magnification of the opticalsystem by obtaining the detection result from the detector 212.

The OIS lens 220 is a lens for correcting a blur of a subject imageformed at the optical system of the interchangeable lens 200. The OISlens 220 moves in the direction to cancel out the shake of the camerasystem 1, thereby reducing the blur of the subject image formed on theCCD image sensor 110. The OIS lens 220 includes a single or a pluralityof lenses. An actuator 221 is controlled by an IC 223 for OIS to drivethe OIS lens 220 in a plane perpendicular to the optical axis of theoptical system. The actuator 221 can be implemented by, for example, amagnet and a planar coil. A position detection sensor 222 is a sensorthat detects the position of the OIS lens 220 on a plane perpendicularto the optical axis of the optical system. The position detection sensor222 can be implemented by, for example, a magnet and a Hall element. TheIC 223 for OIS controls the actuator 221 based on a detection result ofthe position detection sensor 222 and a detection result of a camerashake detector such as a gyro sensor. The IC 223 for OIS obtains thedetection result of the camera shake detector, from the lens controller240. Further, the IC 223 for OIS sends, to the lens controller 240, asignal that represents the state of an optical image blur correctionprocess.

The focus lens 230 is a lens for changing with the optical system thefocus state of a subject image formed on the CCD image sensor 110. Thefocus lens 230 includes a single or a plurality of lenses.

A focus motor 233 drives the focus lens 230 to move forward and backwardalong the optical axis of the optical system based on the control of thelens controller 240. Thus, the focus state of the subject image formedon the CCD image sensor 110 through the optical system can be changed.In the present embodiment, a DC motor can be used as the focus motor233. However, the present invention is not limited thereto, and thefocus motor 233 can be implemented by a stepping motor, a servo motor,an ultrasonic motor, or the like.

A first encoder 231 and a second encoder 232 are each a conventionaloptical encoder structured with a rotating member and a photocoupler,and detect the rotation of the focus motor 233. The lens controller 240counts detection signals from the first and second encoders 231 and 232with a counter 243 installed therein. Respective detection signals ofthe first encoder 231 and the second encoder 232 are out of phase witheach other. Therefore, by counting the detection signals of the firstencoder 231 and the detection signals of the second encoder 232 incombination, the rotation direction of the focus motor 233 can bedetected. The lens controller 240 can recognize a move amount or theposition of the focus lens by the value of the counter 243.

The lens controller 240 controls the focus motor 233 in a first controlmode or a second control mode. In the first control mode, the lenscontroller 240 controls the focus motor 233 using only the detectionsignals from the first encoder 231. Because only the detection signalsfrom the first encoder 231 are used in the first control mode, therotation direction of the focus motor 233 cannot be detected. On theother hand, in the second control mode, the lens controller 240 controlsthe focus motor 233 using the first encoder 231 and the second encoder232. In the second control mode, the lens controller 240 can also detectthe drive direction of the focus lens 230.

The lens controller 240 controls the IC 223 for OIS, the focus motor 233and the like based on a control signal from the camera controller 140,thereby controlling the entire interchangeable lens 200. Further, thelens controller 240 receives signals from the detector 212, the IC 223for OIS, the first encoder 231, the second encoder 232 and the like, andsends the signals to the camera controller 140. The data exchangebetween the lens controller 240 and the camera controller 140 isperformed through the lens mount 250 and the body mount 150. The lenscontroller 240 uses DRAM 241 as working memory in exerting control.Further, flash memory 242 stores programs, parameters and the like foruse in control exerted by the lens controller 240.

Here, the parameters stored in the flash memory 242 include drivefrequency information of the focus lens 230 in the interchangeable lens200. The drive frequency information is information on an operationfrequency at which the focus lens 230 is caused to periodically moveforward and backward along the optical axis (hereinafter, such anoperation is referred to as “wobbling operation”) for an autofocusoperation in capturing a moving image. For example, an interchangeablelens capable of capturing a moving image at a plurality of frame ratesis required to move the focus lens forward and backward along theoptical axis at a plurality of types of frequencies. Accordingly, inthis case, the flash memory 242 stores a plurality of pieces of drivefrequency information. The drive frequency information stored in theflash memory 242 will be described in more detail below.

1-1-4. Drive Frequency Information

FIGS. 2A and 2B are schematic diagrams for describing the drivefrequency information of the focus lens 230 according to the presentembodiment.

The camera body 100 according to the present embodiment can capture amoving image at two types of frame rate, namely 59.94 (field/sec) and 24(frame/sec). Here, 59.94 (field/sec) is a frame rate of a moving imagecomplying with the NTSC (National Television Standards Committee)standard. In the present embodiment, a mode for capturing a moving imageat 59.94 (field/sec) is referred to as “a normal mode”, and a mode forcapturing a moving image at 24 (frame/sec) is referred to as “a cinemamode”. It is noted that the normal mode captures a moving image aninterlace format, and the cinema mode captures a moving image in aprogressive format. It is further noted that one frame corresponds totwo fields.

Here, an autofocus method for a subject image in capturing a movingimage using the camera system 1 will be described. Every time the camerasystem 1 captures an image of one field (in the normal mode) or oneframe (in the cinema mode), the camera system 1 performs an operation tomove the focus lens 230 forward and backward along the optical axis (thewobbling operation). For example, when capturing a moving image in thenormal mode, as shown in FIG. 2A, the camera system 1 moves the focuslens 230 forward and backward along the optical axis at a frequency of29.97 (Hz). Further, when capturing a moving image in the cinema mode,as shown in FIG. 2B, the camera system 1 moves the focus lens 230forward and backward along the optical axis at a frequency of 12 (Hz).Every time the camera system 1 captures an image of one field (in thenormal mode) or one frame (in the cinema mode) and generates image data,the camera system 1 calculates an evaluation value for the autofocusoperation of the generated image data (hereinafter, referred to as “theAF evaluation value”). Specifically, a brightness signal is obtainedbased on the image data generated by the CCD image sensor 110. Then,high frequency components of the brightness signal in the screen areaccumulated to obtain the AF evaluation value.

In this manner, every time the camera system 1 generates image data oftwo fields (in the normal mode) or two frames (in the cinema mode), thecamera system 1 calculates an AF evaluation value for each of the statein which the focus lens 230 is shifted from the current position towardthe subject along the optical axis direction and the state in which thefocus lens 230 is shifted toward the CCD image sensor 110. By comparingthese two AF evaluation values with each other, the camera system 1determines whether the focus lens 230 should be shifted from the currentposition toward the subject or toward the CCD image sensor 110 in thefollowing period. By moving the focus lens 230 forward and backwardalong the optical axis in this manner, the camera system 1 cancontinuously focus on the subject image in capturing a moving image.

Meanwhile, in order to drive the focus lens 230 at a predeterminedfrequency as described above, it is necessary to store in advance aprogram for driving the focus motor 233 at a predetermined frequency inthe flash memory 242 of the interchangeable lens 200. On the other hand,the camera body 100 can be mounted with a variety of interchangeablelenses. For example, it is also possible to be mounted with aninterchangeable lens that does not support a drive frequency of 12 (Hz)of the focus lens. In such a case, if the camera body 100 instructs theinterchangeable lens to move the focus lens forward and backward alongthe optical axis at 12 (Hz), then there arises a possible risk ofmalfunction of the interchangeable lens.

Accordingly, in the present embodiment, the interchangeable lens 200stores information (drive frequency information) on a drivable frequencyto move the focus lens 230 forward and backward along the optical axisin the flash memory 242. For example, when the interchangeable lens 200is drivable along the optical axis at two frequencies, namely 12 (Hz)and 29.97 (Hz), the drive frequency information indicating that theinterchangeable lens 200 supports two types of drive frequency of 12(Hz) and 29.97 (Hz) is stored in the flash memory 242. Storing the drivefrequency information in the flash memory 242 in this manner allows theinterchangeable lens 200 to inform in advance the camera body 100 of thedrive frequency of the focus lens 230 which the interchangeable lens 200can support.

Further, by making it possible to drive the focus lens 230 at two typesof frequencies of 12 (Hz) and 29.97 (Hz), the camera system 1 is allowedto capture a moving image at two types of frame rate. It is noted that,in the present embodiment, information that represents numerical valuesthemselves, such as 12 (Hz) and 29.97 (Hz), is stored in the flashmemory 242 as the drive frequency information.

The focus lens 230 is one example of a focus lens. The focus motor 233is one example of a driving unit. The lens controller 240 is one exampleof a lens controller. The flash memory 242 is one example of a storageunit. The CCD image sensor 110 is one example of an imaging unit. Theframe rate selection dial 131 is one example of a receiving unit. Thecombination including the camera controller 140 and the body mount 150is one example of an obtaining unit. The camera controller 140 is oneexample of a body controller. The liquid crystal display monitor 120 isone example of a display unit.

1-2. Operation 1-2-1. Imaging Preparation Operation

An operation of the camera system 1 in preparation for capturing animage will be described. FIG. 3 shows signal sending and receiving inthe imaging preparation operation of the camera system 1.

In a state where the interchangeable lens 200 is mounted to the camerabody 100, when the user turns on the camera body 100, the power supply160 supplies power to the interchangeable lens 200 through the bodymount 150 and the lens mount 250 (S11). Next, the camera controller 140requests authentication information of the interchangeable lens 200 fromthe lens controller 240 (S12). Here, the authentication information ofthe interchangeable lens 200 includes information on whether or not theinterchangeable lens 200 is mounted and information on whether or notaccessories are mounted. The lens controller 240 responds to the lensauthentication information request from the camera controller 140 (S13).

Next, the camera controller 140 requests the lens controller 240 toperform an initialization operation (S14). In response thereto, the lenscontroller 240 performs the initialization operation, such as reset of adiaphragm and reset of the OIS lens 220. Then, the lens controller 240sends to the camera controller 140 a response indicating that the lensinitialization operation has been completed (S15).

Next, the camera controller 140 requests lens data from the lenscontroller 240 (S16). The lens data is stored in the flash memory 242.The lens controller 240 reads lens data from the flash memory 242, andsends the lens data to the camera controller 140 (S17). Here, the lensdata is a characteristic value specific to the interchangeable lens 200,such as a lens name, F-number, a focal length and the like.

In particular, in the present embodiment, the lens data includes drivefrequency information. This makes it possible for the camera body 100 toobtain the drive frequency information on the drive frequency of thefocus lens 230 supported by the interchangeable lens 200 at the imagingpreparation stage. That is, the camera body 100 can obtain, at thisstage, the information indicating that the interchangeable lens 200 canmove the focus lens 230 forward and backward along the optical axis attwo types of drive frequencies, namely 12 (Hz) and 29.97 (Hz).

When the camera controller 140 recognizes the lens data of theinterchangeable lens 200 mounted to the camera body 100, the cameracontroller 140 becomes in a state capable of capturing an image. In thisstate, the camera controller 140 requests periodically the lens statedata indicative of the state of the interchangeable lens 200 from thelens controller 240 (S18). The lens state data includes, for example,zoom magnification information attained by the zoom lens 210, positionalinformation of the focus lens 230, aperture value information and thelike. In response to the request, the lens controller 240 sends therequested lens state data to the camera controller 140 (S19).

1-2-2. Operation of Capturing Moving Image

A description will be given of the operation of capturing a moving imageperformed by the camera system 1 having completed the imagingpreparation in the above manner, with reference to FIG. 4. FIG. 4 is aflowchart related to control of the camera system 1 in capturing amoving image with the camera system 1.

At the imaging preparation stage, when the power supply of the camerabody 100 is turned on (S30), the camera body 100 obtains the drivefrequency information of the focus lens 230 from the interchangeablelens 200 (S31). At this stage, the camera body 100 stands by until arecording mode is selected by the user (S32). Here, the recording moderefers to a mode for shooting a still image or a mode for shooting amoving image.

When the recording mode is selected by the user, the camera controller140 determines whether the selected recording mode is a still imagerecording mode or a moving image recording mode (S33).

When it is determined to be the still image recording mode, the camerabody 100 shifts to the still image recording mode, and stands by untilthe release button 130 is pressed down by the user (S34).

When it is determined to be the moving image recording mode, the cameracontroller 140 determines whether the recording mode selected with theframe rate selection dial 131 is a normal mode or a cinema mode (S35).

When it is determined to be the normal mode, the camera controller 140determines whether or not the mounted interchangeable lens 200 cansupport the normal mode (S36). This determination is made by referringto the drive frequency information obtained from the interchangeablelens 200 at the imaging preparation stage. Specifically, when the drivefrequency information indicates that the interchangeable lens 200 isoperable at 29.97 (Hz), which is the wobbling frequency in the normalmode, it is determined that the interchangeable lens supports the normalmode.

When it is determined that the interchangeable lens 200 supports thenormal mode, the camera controller 140 controls the CCD image sensor 110to capture a moving image at 59.94 (field/sec) (S37). Further, thecamera controller 140 sends a control signal instructing the lenscontroller 240 to move the focus lens 230 forward and backward along theoptical axis at 29.97 (Hz), to the lens controller 240 (S37). In otherwords, when a drive frequency of 29.97 (Hz) corresponding to the normalmode selected by the user agrees with any of pieces of the driveinformation indicated by the drive frequency information obtained fromthe interchangeable lens 200, the camera controller 140 controls the CCDimage sensor 110 to capture the subject image at 59.94 (field/sec)indicated by the normal mode, and sends the interchangeable lens 200 acontrol signal instructing to drive the focus lens 230 at a drivefrequency of 29.97 (Hz) corresponding to the normal mode. Thus, in thepresent embodiment, with respect to the interchangeable lens 200supporting the normal mode, the camera controller 140 outputs a controlsignal to the lens controller 240 to drive the focus lens 230 at a drivefrequency corresponding to the normal mode. In this manner, only when aninterchangeable lens that can support a frame rate instructed by theuser is mounted, the focus lens can be controlled at the drive frequencycorresponding to the frame rate instructed by the user.

On the other hand, when it is determined that the interchangeable lens200 does not support the normal mode, the camera controller 140 controlsthe liquid crystal display monitor 120 to display a warning (S38). Inthis case, because the wobbling operation for carrying out the autofocusoperation cannot be performed, a warning is displayed, such as shown inFIG. 5, indicating that an autofocus operation is impossible. In thismanner, when the currently mounted interchangeable lens does not supportthe normal mode (for example, in a case where a lens that does notsupport autofocus in capturing a moving image is mounted), the camerabody 100 informs the user that the autofocus operation is impossiblethrough the display on the liquid crystal display monitor 120. Thiswarning allows the user to recognize that the currently mountedinterchangeable lens cannot achieve the autofocus operation in thenormal mode, and perform the manual operation as necessary. Further, thecamera body 100 does not instruct the interchangeable lens 200 toperform the autofocus operation. Accordingly, a possible risk ofmalfunction of the interchangeable lens not supporting the normal modecan be suppressed.

In the present embodiment, it is configured that, when aninterchangeable lens not supporting the selected normal mode is mountedto the camera body 100, the camera body 100 displays a warning throughthe liquid crystal display monitor 120 and does not issue an instructionto move the focus lens forward and backward along the optical axis atthe non-supported drive frequency. However, the present embodiment isnot limited to such a configuration. For example, when aninterchangeable lens not supporting the normal mode is mounted, a movingimage may be captured by manually controlling the focus. This allows amoving image to be captured even in a case where an interchangeable lensnot supporting the normal mode is mounted. Further, in a case where aninterchangeable lens not supporting the normal mode is mounted, themoving image may be captured while adjusting the focus based on a driveamount of the focus lens which is informed successively by the camerabody to the interchangeable lens. This allows a moving image to becaptured while adjusting the focus, even in a case where aninterchangeable lens not supporting the normal mode is mounted.

Returning to FIG. 4, in step S35, when the recording mode selected withthe frame rate selection dial 131 is determined to be the cinema mode,the camera controller 140 determines whether or not the currentlymounted interchangeable lens 200 can support the cinema mode (S39). Thisdetermination is made based on the drive frequency information obtainedat the imaging preparation stage from the interchangeable lens 200.Specifically, when the drive frequency information indicates that theinterchangeable lens 200 is drivable at (Hz), which is the wobblingfrequency in the cinema mode, it is determined that the interchangeablelens 200 supports the cinema mode.

When it is determined that the interchangeable lens 200 supports thecinema mode, the camera controller 140 controls the CCD image sensor 110to capture a moving image at 24 (frame/sec) (S40). Further, the cameracontroller 140 instructs the lens controller 240 to move the focus lens230 forward and backward along the optical axis at (Hz) (S40). Thus, inthe present embodiment, when the interchangeable lens 200 supports thecinema mode, the camera controller 140 sends a control signal to thelens controller 240 instructing it to drive the focus lens 230 at adrive frequency supporting the cinema mode. In this manner, only whenthe interchangeable lens that can support the frame rate instructed bythe user is mounted, the focus lens can be controlled at a drivefrequency corresponding to the frame rate instructed by the user.

On the other hand, when it is determined that the interchangeable lens200 does not support the cinema mode, the camera controller 140 controlsthe liquid crystal display monitor 120 to display a warning (S41). FIG.6 shows an example of the warning display. In this manner, when thecurrently mounted interchangeable lens does not support the cinema mode,the camera body 100 informs the user of the fact through the display onthe liquid crystal display monitor 120. This warning allows the user torecognize that the currently mounted interchangeable lens does notsupport the cinema mode. Further, the camera body 100 does not instructthe interchangeable lens to move the focus lens 230 forward and backwardalong the optical axis at the drive frequency which is not supported bythe interchangeable lens. Accordingly, a possible risk of malfunction ofthe interchangeable lens not supporting the cinema mode can besuppressed.

In the first embodiment, it is configured that, when an interchangeablelens not supporting the cinema mode is mounted, the camera body 100displays a warning through the liquid crystal display monitor 120, anddoes not issue an instruction to move the focus lens forward andbackward along the optical axis at the non-supported drive frequency.However, the present embodiment is not limited to such an arrangement.For example, when an interchangeable lens not supporting the cinema modeis mounted, a moving image may be captured by manually controlling thefocus. This allows a moving image to be captured even in a case where aninterchangeable lens not supporting the selected moving image recordingmode is mounted. Further, in a case where an interchangeable lens notsupporting the cinema mode is mounted, the moving image may be capturedwhile adjusting the focus based on a drive amount of the focus lenswhich is successively informed by the camera body. This allows a movingimage to be captured while adjusting the focus, even in a case where aninterchangeable lens not supporting the cinema mode is mounted. Further,in a case where an interchangeable lens not supporting the cinema modebut supporting the normal mode is attached, a moving image may becaptured by switching the mode to the normal mode instead of the cinemamode. This allows a moving image to be captured while adjusting thefocus, even in a case where an interchangeable lens not supporting thecinema mode is mounted.

Other Embodiments

In the foregoing, the first embodiment has been described as oneembodiment of the present invention. However, the embodiments of thepresent invention are not limited thereto. In the following, otherembodiments will be described.

In the first embodiment, the camera body 100 is capable of capturing amoving image at a frame rate of 59.94 (field/sec) in the normal mode.However, the frame rate in the normal mode is not limited thereto.Specifically, the camera body 100 may be configured to be capable ofcapturing a moving image at a frame rate of 50 (field/sec). This allowsthe camera body 100 to capture a moving image complying with the PALstandard. Further, the camera body 100 may support both the frame rates,i.e., 59.94 (field/sec) and 50 (field/sec).

In the first embodiment, the camera body 100 is capable of capturing amoving image at 24 (frame/sec) in the cinema mode. However, the framerate of the cinema mode is not limited thereto. Specifically, it is alsopossible to define the mode of capturing a moving image at a frame ratesuch as 25 (frame/sec), 26 (frame/sec), 30 (frame/sec) or the like, asthe cinema mode.

In the first embodiment, the drive program is stored in the flash memory242 of the interchangeable lens 200. However, the present embodiment isnot limited thereto. Specifically, a dedicated storage medium forstoring the drive program may be provided to the interchangeable lens200 to store the program therein.

In the first embodiment, the focus lens 230 is always caused to performthe wobbling operation when capturing a moving image. However, thepresent embodiment is not limited thereto. Specifically, it may also bepossible to prepare the autofocus control and the manual focus controlas the methods for controlling the focus lens in capturing a movingimage. In such a case, the control shown in the first embodiment may beexerted when the autofocus control mode is selected.

In the first embodiment, the configuration of the interchangeable lens200 is exemplarily shown as having the zoom lens 210 and the OIS lens220. However, these are not the essential matters. Specifically, theidea of the first embodiment is also applicable to a camera systemmounted with a single focus lens without the zoom function. Further, theidea of the first embodiment is also applicable to a camera systemmounted with an interchangeable lens without the camera shake correctionfunction (image stabilizer).

In the first embodiment, the camera body without a movable mirror hasbeen exemplarily shown. However, the camera body may house therein amovable mirror. Further, the camera body may house therein a prism forseparating the subject image. Still further, the movable mirror may behoused not inside the camera body but inside an adaptor.

In the first embodiment, the CCD image sensor 110 has been exemplarilyshown as an imaging device. However, the imaging device is not limitedthereto. For example, the imaging device may be a CMOS image sensor oran NMOS image sensor.

In the first embodiment, as the drive frequency information, informationsuch as 12 (Hz) and 29.97 (Hz) that represents the numerical valuesthemselves is used. However, the expression of the drive frequencyinformation is not limited thereto. For example, the drive frequency maybe expressed by codes. Specifically, it is also possible to previouslydefine that “01” represents 12 (Hz) and “10” represents 29.97 (Hz).Then, the drive frequency information as being expressed as the codessuch as “01” and “10” may be stored in the flash memory 242. In thismanner, the storage capacity consumed on the flash memory 242 can bereduced.

In the first embodiment, one wobbling frequency is set to the imagingfrequency (hereinafter referred to as “the control frequency”) of theCCD image sensor 110. Specifically, a frequency which is half of thecontrol frequency is set as the wobbling frequency. However, a pluralityof wobbling frequencies may be set to one control frequency. Forexample, the frequencies one-half, one-fourth, or one-eighth of thecontrol frequency may be set as the wobbling frequency. The drivefrequency information in such a case may be expressed by informationindicative of a ratio to the control frequency. A specific example insuch a situation will be described below.

FIG. 7 shows a configuration of control frequency support flags showingcontrol frequencies or wobbling frequencies that the interchangeablelens can support. Such control frequency support flags may be sent aslens data from the interchangeable lens 200 to the camera body 100. Thecontrol frequency support flags are composed of 15 bits, each bitcomposing a flag. Each of the first to twelfth bits is a flag indicativeof whether or not the interchangeable lens 200 supports the controlfrequency corresponding to each flag. Each of the thirteenth tofifteenth bits is a flag indicative of whether or not theinterchangeable lens 200 can perform the wobbling operation at afrequency one-nth (n=2, 4, and 8) of the supported control frequency.Every flag has the value 1 representing “supported”, and the value 0representing “not supported”. For example, when the 60 Hz controlfrequency support flag as the second bit and the ½ wobbling frequencysupport flag as the thirteenth bit are both “1”, the interchangeablelens 200 is drivable at a control frequency of 60 Hz, and is capable ofperforming the wobbling operation at half (30 Hz) of the controlfrequency. In this case, the 1/n wobbling frequency support flag (n=2,4, and 8) as the thirteenth to fifteenth bits correspond to the drivefrequency information.

In the first embodiment, the image data captured at an imaging frequencyof 24 (frame/sec) (cinema mode) is recorded as the image data of 24(frame/sec), and the image data captured at an imaging frequency of59.94 (field/sec) (normal mode) is recorded as the image data of 59.94(field/sec). However, the present embodiment may not necessarily havesuch a structure. For example, the image data captured at an imagingfrequency of 24 (frame/sec) may be recorded as the image data of 60(field/sec). Specifically, while capturing at an imaging frequency of 24(frame/sec), by performing a process of distributing the captured twoframes into five fields (a so-called 2-3 pull-down process), the imagedata of 60 (field/sec) may be generated. In this manner, based on theimage data captured at an imaging frequency of 24 (frame/sec), the imagedata of 60 (field/sec) can be generated. As a result, even when aninterchangeable lens that can only support the wobbling at the frequencycorresponding to an imaging frequency of 24 (frame/sec) is mounted tothe camera body, the camera body can generate the image data of 60(field/sec) while exerting the wobbling control over the interchangeablelens.

INDUSTRIAL APPLICABILITY

The present invention is applicable to an interchangeable lens mountableto a camera body, a camera body to which an interchangeable lens ismountable, and an interchangeable lens type camera system. Specifically,the present invention can be applied to a digital still camera, a moviecamera, and the like.

DESCRIPTION OF REFERENCE SIGNS

-   1 Camera system-   100 Camera body-   110 CCD image sensor-   112 Timing generator-   130 Release button-   140 Camera controller-   200 Interchangeable lens-   230 Focus lens-   231 First encoder-   232 Second encoder-   233 Focus motor-   240 Lens controller

1. An interchangeable lens mountable to a camera body, comprising: afocus lens configured to change a focus state of a subject image; adriving unit configured to drive the focus lens along an optical axis; alens controller configured to control the driving unit to move the focuslens forward and backward at a predetermined drive frequency along theoptical axis; a storage unit configured to store drive informationindicating that the driving unit can drive the focus lens forward andbackward along the optical axis; and a sending unit configured to sendthe drive information to the camera body.
 2. The interchangeable lensaccording to claim 1, wherein the storage unit further stores drivefrequency information indicating a drive frequency at which the drivingunit can drive the focus lens.
 3. The interchangeable lens according toclaim 2, wherein the storage unit is configured to store the drivefrequency information on a plurality of types of drive frequencies. 4.The interchangeable lens according to claim 2, wherein the drivefrequency information is represented by a reference drive frequency anda ratio to the reference drive frequency.
 5. The interchangeable lensaccording to claim 2, wherein the lens controller is configured tocontrol such that the drive information and/or the drive frequencyinformation stored in the storage unit are/is sent to the camera bodythrough the sending unit in response to a request from the camera body.6. A camera body to which an interchangeable lens is mountable, theinterchangeable lens including a focus lens and storing driveinformation indicating that the focus lens can be driven forward andbackward along the optical axis, the camera body comprising: an imagingunit configured to capture a subject image; an obtaining unit configuredto obtain the drive information from the interchangeable lens; and abody controller configured to control an operation of the camera body byreferring to the drive information obtained by the obtaining unit. 7.The camera body according to claim 6, wherein the storage unit furtherstores drive frequency information indicating a drive frequency at whichthe driving unit can drive the focus lens, the interchangeable lensfurther includes a sending unit configured to send the drive informationand/or the drive frequency information to the camera body, the obtainingunit obtains the drive frequency information from the interchangeablelens through the sending unit, the imaging unit captures a subject imageat a predetermined imaging frequency, the camera body further includes areceiving unit configured to receive an instruction related to thepredetermined imaging frequency, the body controller determines whetherthe focus lens can be driven at a drive frequency corresponding to thepredetermined imaging frequency indicated by the instruction received bythe receiving unit, by referring to the drive frequency informationobtained by the obtaining unit, and controls the operation of the camerabody according to the result of the determining.
 8. The camera bodyaccording to claim 6, wherein the drive frequency information isrepresented by a reference drive frequency and a ratio to the referencedrive frequency.
 9. The camera body according to claim 7, furthercomprising a sending unit configured to send a control signal to theinterchangeable lens, wherein the body controller controls the sendingunit to send a control signal for controlling the focus lens accordingto the result of the determining.
 10. The camera body according to claim7, wherein wherein when the body controller, referring to the obtaineddrive frequency information, determines that the focus lens can bedriven at the drive frequency corresponding to the imaging frequencyindicated by the received instruction, the body controller controls theimaging unit to capture an image at the imaging frequency indicated bythe received instruction, and further controls the sending unit to senda control signal for driving the focus lens at the drive frequencycorresponding to the imaging frequency indicated by the receivedinstruction to the interchangeable lens.
 11. The camera body accordingto claim 7, further comprising a display unit capable of displayingwarning information, wherein when the body controller, referring to theobtained drive frequency information, determines that the focus lens cannot be driven at the drive frequency corresponding to the predeterminedimaging frequency indicated by the received instruction, the bodycontroller controls the display unit to display the warning information.12. The camera body according to claim 7, further comprising a sendingunit configured to send a control signal to the interchangeable lens,wherein when the body controller, referring to the obtained drivefrequency information, determines that the focus lens can not be drivenat the drive frequency corresponding to the predetermined imagingfrequency indicated by the received instruction, the body controllercontrols the sending unit to be prevented from sending a control signalfor driving the focus lens at the drive frequency corresponding to thepredetermined imaging frequency indicated by the received instruction tothe interchangeable lens.
 13. The camera body according to claim 7,further comprising a sending unit to send a control signal to theinterchangeable lens, wherein the body controller control the sendingunit to send a request signal for requesting the drive frequencyinformation to the interchangeable lens.
 14. A camera system comprisingan interchangeable lens and a camera body, the interchangeable lenscomprising: a focus lens configured to change a focus state of a subjectimage; a driving unit configured to drive the focus lens along anoptical axis; a lens controller configured to control the driving unitto move the focus lens forward and backward at a predetermined drivefrequency along the optical axis; a storage unit configured to storedrive information indicating that the driving unit can drive the focuslens forward and backward along the optical axis, and a sending unit tosend the drive information to the camera body, the camera bodycomprising: an imaging unit configured to capture a subject; a bodycontroller configured to control the camera body, wherein the bodycontroller requests the drive information from the lens controller, thelens controller sends the drive information to the body controllerthrough the sending unit in response to the request from the bodycontroller, and the body controller controls an operation of the camerabody by referring to the received drive information.
 15. The camerasystem according to claim 14, wherein the storage unit further storesdrive frequency information indicating a drive frequency at which thefocus lens can be driven, the body controller requests the drivefrequency information from the lens controller, the lens controllersends the drive frequency information through the sending unit to thebody controller in response to the request from the body controller, theimaging unit captures an image at a predetermined imaging frequency, thecamera body further includes a receiving unit configured to receive aninstruction related to the predetermined imaging frequency, the bodycontroller, referring to the received drive frequency information,determines whether the focus lens can be driven at a drive frequencycorresponding to the predetermined imaging frequency indicated by theinstruction received by the receiving unit and controls the operation ofthe camera body according to the result of the determining.
 16. Thecamera system according to claim 15, wherein the drive frequencyinformation is represented by a reference drive frequency and a ratio tothe reference drive frequency.